13 research outputs found
Thermal and dynamic range characterization of a photonics-based RF amplifier
No full textThis work reports a thermal and dynamic range characterization of an ultra-wideband photonics-based RF amplifier for microwave and mm-waves future 5G optical-wireless networks. The proposed technology applies the four-wave mixing nonlinear effect to provide RF amplification in analog and digital radio-over-fiber systems. The experimental analysis from 300 kHz to 50 GHz takes into account different figures of merit, such as RF gain, spurious-free dynamic range and RF output power stability as a function of temperature. The thermal characterization from -10 to +70 °C demonstrates a 27 dB flat photonics-assisted RF gain over the entire frequency range under real operational conditions of a base station for illustrating the feasibility of the photonics-assisted RF amplifier for 5G networks
Implementation of a Broadband Photonics-assisted RF Amplifier Toward 5G Networks
No full textWe report the implementation of a photonics-assisted RF amplifier for broadband and multiband 5G networks. A 2 Gsymb/s signal with different digital modulation formats at 20 GHz and a 100 Msymb/s high-order digital modulated signal at 6 GHz have been used for characterizing the proposed technology as a function of the RF gain, signal-to-noise ratio and error vector magnitude. Experimental results demonstrate RF amplification, reconfigurability, distortion absence and low phase noise levels through 6, 20 and 38 GHz frequency bands, which have been considered potential for the future 5G networks
Thermal performance analysis of an all-optical and ultra-wideband RF amplification method for 5G networks
No full textSan José de Urrao
No full textSan José de Urrao es un poblado perteneciente al corregimiento de la Encarnación, Urrao. Ubicado en la subregión suroeste del departamento de Antioquia y fundado en 1781. Este mapa, elaborado en tinta sobre papel, representa el territorio físico de San José de Urrao en 1793, contiene cartela con la ubicación de los siguientes puntos: A. Salaos de Noque; B. Alto del Obispo; C. Alto de Nongobarco, D. Quebrada de las Juntas, E. Alto de Frontino; F. Cabeceras de Urrao; G. Arcabuco o amagamento que nace del alto de Nongobarco, H. Primer paso del Río de Urrao, Y. Desemboque de la quebrada de Aná a Urrao, Y. Nacimiento de la misma quebrada (Aná), H. Segundo paso del Río de Urrao, J. Sitio de San José de Urrao, P. Río de Penderisco; R. Llanos de la venta
Arcs de bois contreplaque de pine caraïbe du venezuela. Une proposition pour des processus de l´architecture eco-durable
No full textThe main principle of laminated wood for buildings establishes that some weak and small sawn pieces, when joined with an artificial adhesive, make up a larger element with physical-mechanical properties superior to the ones of the same timber species in original condition. The use of pinus caribaea Morelet, var. hondurensis laminated wood, cultivated in the forests of the Venezuelan Orinoquia, is analyzed in this research in order to supply raw material in the manufacture of structural components for different static systems, which part from the horizontal straight beam, simply supported on vertical columns; up to the two or three joints arches, within the building procedures of ecological and sustainable constructions. It is proposed as a general objective to define an arch model as a structural element which simplifies production, transportation, preassembly, assembly, exploitation, transformability, deconstruction and recycling tasks; that justifies the principles of eco-sustainable technology development based on the application of Caribbean pine wood. Among conclusions, it is determined that eco-sustainability in architecture is defined as the set of measures that result in an environmentally friendly constructive solution; which also uses materials of natural origin respecting ecosystems, builds without waste; deconstructs and recycles without demolishing or generating waste. This article is included in the line of research called: Technological Innovation as a Process; Sub-line: Assimilation and Technological Dominance; of the Research and Development Management Master Degree - Economic and Social Sciences Faculty of Central University of Venezuela. Key words: Arches, eco-sustainable architecture, Orinoquia forests, structural components, laminated wood, Caribbean pine, technology. El principio generador de la madera laminada establece que piezas aserradas, débiles y pequeñas, al unirse con adhesivos artificiales, conforman elementos más grandes, con propiedades físico-mecánicas superiores a las de la misma especie maderable. En esta investigación se analiza la aplicación de la madera laminada del Pinus caribaea Morelet, var. hondurensis; cultivado en la Orinoquia venezolana, para fabricar sistemas estáticos curvos, dentro de procedimientos edificatorios en construcciones ecológicas y sustentables. El objetivo general propone definir un modelo estructural de arcos que simplifique las labores de producción, transporte, pre-ensamblado, montaje, aprovechamiento, transformabilidad, deconstrucción y reciclaje; que justifique los principios de desarrollo tecnológico ecosustentable basados en las innovaciones tecnológicas de la madera laminada de pino Caribe. La metodología empleada permitió analizar comparativamente y describir los predimensionamientos del peralte de distintos componentes estructurales portantes, que responden eficientemente a esfuerzos de flexo-compresión, configurados a partir de los diagramas de momentos flexionantes de vigas rectas simplemente apoyadas y empotradas y son geométricamente análogos a sistemas de arcos bi o triarticulados. Entre las conclusiones se determina que la arquitectura ecosustentable queda definida como el conjunto de medidas que aportan soluciones constructivas que no dañan el medio ambiente; que emplea, además, materiales naturales renovables, respeta los ecosistemas, construye sin desperdicios; que deconstruye y recicla, sin demoler ni generar escombros. Este artículo queda incluido en la línea de Investigación: Innovación Tecnológica como Proceso; sub-línea: Asimilación y Dominio Tecnológico; Postgrado de Gestión de Investigación y Desarrollo - Facultad de Ciencias Económicas y Sociales de la Universidad Central de Venezuela. Palabras clave: Arcos, arquitectura ecosustentable, bosques de la Orinoquia, madera laminada, pino Caribe. Mots-clés: arches, architecture éco-durable, forêts de l\u27Orénoque, bois stratifié, pin CaraïbeLe principe de génération de bois stratifié pour structures indique que plusieurs pièces sciés, faibles et petites, quand elles sont unies par adhésives artificielles, forment un plus grand élément, avec des propriétés physico-mécaniques plus élevés que celles des mêmes espèces de bois à l\u27état originel. Dans cette recherche on analyse l\u27application de bois stratifié de Pinus caribaea Morelet var. hondurensis; cultivées dans les forêts de l´ Orinoquia Vénézuélienne, pour fournir la matière première dans la fabrication de composants structurels pour les systèmes statiques différents, qui partent de la poutre horizontale, simplement en appui sur des colonnes verticales, jusqu´a les arcs de deux ou trois articulations dans les procédures édificatrices de constructions écologiques et durables. Il est l\u27objectif général de définir un modèle d\u27arc comme élément structurel qui simplifie les tâches de production, de transport, des procédures de préassemblé, de montage, de l\u27utilisation, d´être transformable, de déconstruction et de recyclage; qui justifie les principes du développement technologique éco-durable, basés sur l\u27application de bois contreplaqué de pin Caraïbe. Parmi les conclusions, il est déterminé que l\u27architecture de Eco soutenabilité est définie comme l\u27ensemble des mesures prises pour obtenir comme résultat une solution constructive respectueuse de l\u27environnement; qui utilise également des matériaux naturels, qui respect les écosystèmes, qui construit sans déchets; qui déconstruit et recycle, sans démolir ou générer des débris. Cet article est inclus dans la recherche: l\u27innovation technologique comme un processus; sous ligne: Assimilation et domaine tecnologique; Master in Management de la Recherche et développement - Faculté des sciences économiques et sociales de l\u27Université centrale du Venezuela. Mots-clés: arches, architecture éco-durable, forêts de l\u27Orénoque, composants de structure, bois stratifié, pin Caraïbe, technologi
Radio over fiber system amplified using technique FWM with reconfigurable antenna frequency
No full text
Arcos con madera laminada del pino caribe venezolano. Una propuesta para procesos de arquitectura ecosustentable
No full text El principio generador de la madera laminada establece que piezas aserradas, débiles y pequeñas, al unirse con adhesivos artificiales, conforman elementos más grandes, con propiedades físico-mecánicas superiores a las de la misma especie maderable. En esta investigación se analiza la aplicación de la madera laminada del Pinus caribaea Morelet, var. hondurensis; cultivado en la Orinoquia venezolana, para fabricar sistemas estáticos curvos, dentro de procedimientos edificatorios en construcciones ecológicas y sustentables. El objetivo general propone definir un modelo estructural de arcos que simplifique las labores de producción, transporte, pre-ensamblado, montaje, aprovechamiento, transformabilidad, deconstrucción y reciclaje; que justifique los principios de desarrollo tecnológico ecosustentable basados en las innovaciones tecnológicas de la madera laminada de pino Caribe. La metodología empleada permitió analizar comparativamente y describir los predimensionamientos del peralte de distintos componentes estructurales portantes, que responden eficientemente a esfuerzos de flexo-compresión, configurados a partir de los diagramas de momentos flexionantes de vigas rectas simplemente apoyadas y empotradas y son geométricamente análogos a sistemas de arcos bi o triarticulados. Entre las conclusiones se determina que la arquitectura ecosustentable queda definida como el conjunto de medidas que aportan soluciones constructivas que no dañan el medio ambiente; que emplea, además, materiales naturales renovables, respeta los ecosistemas, construye sin desperdicios; que deconstruye y recicla, sin demoler ni generar escombros. Este artículo queda incluido en la línea de Investigación: Innovación Tecnológica como Proceso; sub-línea: Asimilación y Dominio Tecnológico; Postgrado de Gestión de Investigación y Desarrollo - Facultad de Ciencias Económicas y Sociales de la Universidad Central de Venezuela. Palabras clave: Arcos, arquitectura ecosustentable, bosques de la Orinoquia, madera laminada, pino Caribe. Mots-clés: arches, architecture éco-durable, forêts de l'Orénoque, bois stratifié, pin Caraïbe</p
Cuphea gracilis Kunth 1824
No full text<p> <b>11.</b> <i>Cuphea gracilis</i> Kunth (1824: 199).</p> <p> <i>Cuphea gracilis</i> var. <i>orinocensis</i> Saint-Hilaire (1833: 100). <i>Cuphea gracilis</i> var. <i>media</i> Koehne (1877: 284).</p> <p> Lectotype (designated by Lourteig 1987: 25):— VENEZUELA. [Amazonas]: “crescit prope Atures, locis arenosis (Orinoco [river]) [approx. 5.612, -67.614]”, May 1800, <i>Humboldt & Bonpland 857</i> (P [00679419] image!, isolectotypes B image!, K [fragm.] image!). Figs. 11A–F, 18.</p> <p> <i>Cuphea multicaulis</i> Koehne (1877: 228). Lectotype (first step designated by Lourteig 1987: 25, <b>second step lectotypification here designated</b>):—[COLOMBIA]. [Vichada]: “ad cataractas Maypures [approx. 5.243, -67.852]”, June 1854, <i>Spruce 3727</i> (P [01901646] image!, isolectotypes BM, F [fragm.] image!, K image!, P [01901647] image!).</p> <p> <i>Cuphea pauciflora</i> Koehne (1903: 132). Lectotype (<b>here designated</b>):— VENEZUELA. “Cuchivero, am Fusse der grossen Stromschnellen”, <i>Selwyn auf der Exp. Passarge n. 809</i> ([illustration] “ <i>C. pauciflora</i> ” in Koehne, Atlas Lythracearum, ined., Gray Herbarium: pl. 75. 1902).</p> <p> <b>Subshrubs</b> 30–50 cm tall; stems erect to decumbent, indumentum strigose and pubescent, one-armed trichomes, and short eglandular trichomes, <0.5 mm long, with curved apices, sometimes concentrated in a longitudinal band along the stem; internodes 0.7–3 cm long; brachyblasts absent. <b>Leaves</b> opposite, membranaceous, petioles ca. 1 mm long, blades 8–30 × 2.5–5 mm, narrow-ovate, apex acute, base acute to obtuse, margin plane to subrevolute, indumentum strigose on both surfaces; hyphodromous, secondary veins rarely visible. <b>Racemes</b> 10–22 cm long, bracteose, simple to compound, elongated, distinct; bracts 3–13 × 1–3 mm, subequal pairs, similar to leaves in shape and indumentum. <b>Flowers</b> alternate; pedicels 2–5 mm long; bracteoles 0.6–0.7 mm long, ovate; floral tubes 6–7 mm long; spur obtuse, deflexed; outer surface purple, indumentum pubescent, mixed with sparse glandular trichomes; inner surface villous behind the stamens, pilose on the rest of the floral tube; petals 6, purple to magenta, subequal, two dorsal 3–3.2 × 1.2– 1.7 mm, obovate, four ventral 2.7–3.4 × 1.2–1.6 mm, obovate; stamens free in the upper third of the floral tube, five antesepalous exserted, four antepetalous subexserted; pistil ca. 3.2 mm long; ovary glabrous; style pilose to glabrous; ovules 3; nectary ca. 0.6 × 0.7, deflexed. <b>Seeds</b> 2–3, 2 × 1.7–1.9 mm, elliptic to obovate, apex retuse, base acute to obtuse, margin obtuse.</p> <p> <b>Phenology:</b> —Collected with flowers and fruits in May, June, July, and September.</p> <p> <b>Distribution and habitat:</b> — Colombia, in department of Vichada, and Venezuela, in Amazonas state (Fig. 18) (Lourteig 1987, 2007); granite outcrops on riverbanks, and Amazonian savannas; 60–80 m elev.</p> <p> <b>Conservation status:</b> — <i>Cuphea gracilis</i> was categorized as Endangered (EN) B1ab(i,ii,iii)+2ab(i,ii,iii), with an estimated EOO of 500 km ² and AOO of 24 km ². It is a narrowly endemic species, whose populations are threatened by massive hydroelectric projects in the rivers where the species is found (Funk <i>et al.</i> 2007).</p> <p> <b>Specimens examined:</b> —COLOMBIA. <b>Vichada</b>: [Cumaribo], Maipures, plantes des bords de l’Orénoque, <i>Chaffanjon 514</i> (P image!). VENEZUELA. <b>Amazonas</b>: savane d’Atures, plantes des bords de l’Orénoque, 12 June 1887, <i>Gaillard 23</i> (P!); [Atures], Puerto Ayacucho, great rapids of the Orinoco, cristalline laja, 1–1.5 km east of Hotel Amazonas, 07 September 1953, <i>Maguire et al. 36053</i> (P image!); Atures, carretera Puerto Ayacucho-Sanariapo [Samariapo] desde Pto. Ayacucho hasta el Km 35 hacia Sanariapo [Samariapo], en sabana llanera con bosques ocasionales, cerca de la carretera, 6–19 July 1969, <i>Bunting et al. 3500</i> (P image!); [Atures], Puerto Ayacucho, between the electric power plant and the Rio Orinoco, 05º40’00”N, 67º37’00”W, 23 June 1984, <i>Davidse & Miller 26439</i> (P!); Atures, Parque Sucre, on rocky igneous savanna slope just south of Puerto Ayacucho, 05º43’00”N, 67º37’00”W, 08 September 1985, <i>Steyermark et al. 131594</i> (P!); Atures, Rio Sipapo, 5 km de su desembocadura al Rio Orinoco, Cerro Caldero, 05º01’00”N, 67º46’00”W, 17 May 1992, <i>Groger & Barcroft 408</i> (P image!).</p> <p> <i>Cuphea gracilis</i> is characterized by narrow-ovate leaves (Fig. 11B) and long, distinct bracteose racemes (Fig. 11A). It occurs in the border between Venezuela and Colombia, in the granite outcrops on the banks of the Orinoco river and its tributary, the Sipapo river, and in adjacent savanna regions. <i>Cuphea gracilis</i> is morphologically close to <i>C. carajasensis</i>, but can be distinguished by the glabrous ovary, with the villous indumentum present only on the inner surface behind the stamens. In <i>C. carajasensis</i>, the dorsal region of the ovary is densely villous, and is restricted to habitats with ironstone outcrops in the state of Pará, Brazil (Cavalcanti <i>et al.</i> 2016).</p> <p> There are five varieties related to <i>C. gracilis</i>, two described by Saint Hilaire (1833) (<i>C. gracilis var. brasiliensis</i> Saint-Hilaire [1833: 100] and <i>C. gracilis</i> var. <i>orinocensis</i>) and three by Koehne (1877) (<i>C. gracilis</i> var. <i>major</i> Koehne [1877: 284], <i>C. gracilis</i> var. <i>media</i> and <i>C. gracilis</i> var. <i>minor</i> Koehne [1877: 284]). The typification and identity of these varieties are discussed below.</p> <p> In “ <i>Flora Brasiliae Meridionalis</i> ”,Saint Hilaire(1833) made a brief comment contrasting <i>C.gracilis</i> var. <i>orinocensis</i> from <i>C. gracilis</i> var. <i>brasiliensis</i>. There is the remark “ <i>(Humboldtiana)</i> ” right after the name “ <i>Orinocensi</i> ”. The author probably created this variety based on the type of <i>C. gracilis</i>, collected by F.W. von Humboldt and A.J.A. Bonpland. <i>Cuphea gracilis</i> var. <i>brasiliensis</i> was removed from this study because its identification is close to <i>C. retrorsicapilla</i> Koehne (1877: 279), from <i>C</i>. sect. <i>Euandra</i> subsect. <i>Oidemation</i> Koehne (1883: 395, 399) (see discussion in Graham & Cavalcanti 2013).</p> <p> <i>Cuphea gracilis</i> var. <i>media</i> has also been described based on the collection of F.W. von Humboldt & A.J.A. Bonpland, among other specimens (Koehne 1877). However, Lourteig (1987) made a mistake in lectotypifying this variety under “ <i>Spruce 3728</i> ”, since this material is cited by Koehne (1877) for <i>C. gracilis</i> var. <i>minor</i> together with “ <i>Karsten s.n</i>.”. Furthermore, the latter two collections are correctly identified as <i>C. odonellii</i>, thus <i>C. gracilis</i> var. <i>minor</i> was synonymized here under this species.</p> <p> <i>Cuphea gracilis</i> var. <i>major</i> was considered as a synonym of <i>C. antisyphilitica</i> var. <i>acutifolia</i> by Lourteig (1987), who cited a specimen “ <i>Riedel 920</i> ” in P as “ holotype ”. After analyzing the image of the specimen, it was concluded that its morphology is similar to that of members of <i>C</i>. sect. <i>Euandra</i> subsect. <i>Oidemation</i>, however, its identity has not yet been determined.</p> <p> Koehne (1903) placed <i>C. pauciflora</i> in <i>C</i>. sect. <i>Euandra</i> subsect. <i>Hilariella</i> Koehne (1881: 156), because of the length of the stamens and the habit, since he did not see the seeds (the shape of the seed margin is important for infrageneric classification). Lourteig (1987) considered <i>C. pauciflora</i> as a synonym of <i>C. gracilis</i> and commented that she only saw the illustration in Koehne’s unpublished Atlas (“ <i>Atlas Lythracearum</i> ”). In the protologue and illustration there are several striking characters of <i>C</i>. sect. <i>Trispermum</i> s.l., and of <i>C. gracilis</i>, such as delicate branches, long, bracteose racemes, 3 ovules, and vesicles absent. In addition, the collection locality of the type material is close to the occurrence area of <i>C. gracilis</i>. Finally, the species was kept here as a synonym of <i>C. gracilis</i>. In this revision, no specimen related to <i>C. pauciflora</i> was found in the herbaria examined. The species was then lectotypified here with the illustration of the original type material from Koehne’s unpublished Atlas, which includes details of the branches, floral tube in lateral view and in longitudinal-dorsal section, pistil, and nectary.</p>Published as part of <i>Facco, Marlon Garlet & Cavalcanti, Taciana Barbosa, 2023, Taxonomic Revision of Cuphea sect. Trispermum s. l. (Lythraceae), pp. 1921-1935 in Phytotaxa 588 (1)</i> on pages 1921-1935, DOI: 10.11646/phytotaxa.588.1.1, <a href="http://zenodo.org/record/7751590">http://zenodo.org/record/7751590</a>
Исследование характеристик фотодетектора с высоким фототоком при передаче сверхвысокочастотного радиосигнала по оптоволокну
No full textIntroduction. At present, an optical transmission of a microwave signal is of great scientific and practical interest. Moreover, this transmission line can also be used to create microwave photonic devices. Microwave signal losses decrease with an increase of laser power. Commercial photodetectors withstand radiation with a power of several tens of milliwatts. Using a photodetector with a high photocurrent can improve characteristics of photonic transmission lines; in particular, it can reduce microwave signal losses.Aim. Investigation of characteristics of a photodetector with a high photocurrent when transmitting microwave radio signals through optical fiber. Research of microwave signal losses as a function of optical power.Materials and Methods. Experimental studies were carried out on created experimental schemes for studying the characteristics of the photodetector with modulated and unmodulated optical radiation. Theoretical studies were carried out by mathematical modeling of optical path transfer characteristics from the laser power at various powers of an input microwave signal.Results. The dependencies of photocurrent and photovoltage of the photodetector versus laser power were obtained. The experimental amplitude-frequency characteristics of the photonic transmission line were measured at different optical powers. A frequency dependence of the photodetector sensitivity in the range of 0...12 GHz was obtained. Modeling of amplitude-frequency characteristics of the optical path in the range of 0...12 GHz was performed. An approximate frequency dependence of the photodetector sensitivity was obtained.Conclusion. Due to the use of a photodetector with a high photocurrent value and with increasing laser power, microwave losses were reduced to about 10 dB. It was shown that for improving the transmission characteristics of an optical transmission line, it is necessary to use a broadband electro-optical modulator.Введение. В настоящее время большой научный и практический интерес вызывает передача радиочастотного сигнала по оптической линии. Такую линию передачи можно также использовать при создании многих радиофотонных устройств. С ростом мощности используемого лазера снижаются потери СВЧ-сигнала в линии передачи. Однако массово выпускаемые фотодетекторы выдерживают мощность в несколько десятков милливатт. Использование фотодетектора с высоким фототоком позволит улучшить характеристики оптоволоконных линий передачи, в частности, снизить потери при передаче аналогового или цифрового радиочастотного сигнала.Цель. Исследование характеристик фотодетектора с высоким фототоком в системе передачи сверхвысокочастотного радиосигнала по оптоволокну, а также исследование зависимости потерь СВЧ-сигнала от значения мощности оптического излучения в такой системе.Материалы и методы. Экспериментальные исследования проведены на сконструированных экспериментальных схемах для исследования характеристик фотодетектора при модулированном и немодулированном оптическом излучении. Теоретические исследования выполнены математическим моделированием передаточных характеристик оптического тракта при различных мощностях входного СВЧ-сигнала.Результаты. Найдены зависимости фототока и фотонапряжения фотодетектора от мощности излучения лазера. Представлены экспериментальные амплитудно-частотные характеристики (АЧХ) оптической линии передачи, измеренные при различных мощностях оптического излучения. Описан алгоритм получения частотной зависимости чувствительности фотодетектора в диапазоне частот 0...12 ГГц. Приведены результаты теоретического расчета АЧХ линии передачи в указанном диапазоне частот. Получена приближенная частотная зависимость чувствительности фотодетектора.Заключение. За счет использования фотодетектора с высоким значением фототока и повышения мощности лазера до 100 мВт потери СВЧ-сигнала в оптической линии передачи составили около 10 дБ. Показано, что для улучшения передаточных характеристик оптической линии передачи необходимо использовать широкополосный электрооптический модулятор
